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Tower and bow speakers no longer work... troubleshooting steps?


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I have 08 LSV that I purchased last October and at that time sound came out of all the speakers ... recently noticed that the 2 tower and 2 bow no longer work ...4 speakers in sides near driver and observer still work fine.

i have the black jbl box and a single Rockford fosgate amp... see some photos..

I have a multimeter if that helps but access to the amp is not easy (it’s in front of two batteries in the observer compartment).

what are the steps to troubleshoot? In the mux switches I see a front / rear fader which did not seem affect the sound at all ... can’t remember if there was a Mux on off for bow or tower? Separate fuse for either?








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First step is to label any/all wires before disconnection for testing. You don't want to leave this to memory.

It wouldn't seem like tower and bow speakers would be on the same amplifier channels, but they could be on the same side of a source unit fader, although that wouldn't be correct. So check the source fader.

Determine the wiring scheme. And document it. With a 4-channel amplifier, the wiring scheme could be two amplifier channels to two tower speakers, two amplifier channels to four cockpit speakers, two bow speakers driven by the front channels of the black box. The fader would then function as front: all in-boat speakers, and rear: just tower speakers. This scheme would require two RCA cable sets from the black box to amplifier.     

A multimeter helps. A small 9V battery is convenient for testing speakers. A test speaker, just about any speaker, is a handy substitute to confirm there is a signal. A 2-conductor test wire is handy.   

With speakers wires disconnected from the amplifier, use your multimeter to check continuity. A DC resistance of 3 to 5-ohms would indicate one speaker, and a DC resistance of 1.5 to 2.5-ohms would indicate two speakers in parallel. You can also use the 9V battery to create a quick momentary pop to confirm speaker operation.  

You can set your multimeter to AC, and with speakers disconnected, play music to see if the amplifier channel is outputting a signal.

You can disconnect speaker wires at both ends, short together one end, and check for continuity.

You can remove and check speakers with your multimeter for either an open circuit, or a DC resistance that is consistent with the nominal impedance rating (DC resistance is usually only 80% of the rated AC impedance). Or, you can test speakers on a known channel, or test a channel on a known speaker/wire.

You are separating and independently testing a) amplifier, b) speaker wire, & c) speakers, to isolate the culprit. 

If you are only using one set of RCA cables, then confirm that the amplifier input configuration is set so that all 4-channels operate with one stereo input.     


Edited by David
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I was able to test a few things:

1) swapped a bow speaker for a Cavin speaker... bow speaker worked so the bow speakers are good 

2) checked 80 amp circuit breaker ? And it seems to be in the reset position

3) removed the one set of RCA inputs to the amp and the cabin speakers still worked so the amp must power the bow and tower speakers



1) where do I find the on-off switch for that amp ?

2) are there lights that show the amp is working?

3) any reset button for the amp ?

4) where is the volume control for the amp ... I don’t see a Mux button for tower, bow or similar....


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1) this would not be part of the factory setup, and would have been done aftermarket if there is one. So no telling where it could.

2) Typically yes, there is a normal mode light that indicates the amp is on and trying to work. Some amps have a dedicated trouble light, while other simply change the color of the normal light.

3) no

4) no zone or dedicated independent volume for that amp. Master volume and maybe FADE front to rear control. 

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Ok the remote turn on (blue wire from JBL) was not providing + power to the amp. I ran a wire from REM to the Bat + and now see a blue led for power on the amp... progress :)

is that blue wire the best  from JBL to connect to the rem on the P400? The jbl manual says it’s for an “auto ant”

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See if there is a blue/wht wire also. Sometimes, a blue "ANT" wire only has voltage when in tuner mode. If you switch CD, AUX, USB, etc, voltage drops off. The Blue/wht should have voltage all the time the media unit its turned on. 

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